CN104880504A - Pressure difference final motion liquid column balance type coulometry BOD measuring device - Google Patents

Abstract

The invention relates to a differential pressure micro-movement liquid column balance type Coulomb method BOD measuring device, the device comprises a constant temperature control unit and a plurality of Coulomb BOD measuring units arranged in the constant temperature control unit, and the constant temperature control unit comprises a constant temperature water bath , a temperature probe arranged in a constant temperature water bath, a relay electrically connected to the temperature probe in turn, a data acquisition controller, and a cold water heater. It is set in a constant temperature water bath, and connected with a data acquisition controller through circuits respectively. Compared with the prior art, the present invention has simple and compact overall structure, simple operation, stable performance, easy to dismantle, wash and replace the equipment, and the relevant parameters of the test can be automatically monitored, tracked and recorded by computer throughout the whole process, and can be used for various organic substances (such as: Volatility, photolysis, poor solubility, etc.) biodegradation test.

Description

A pressure difference micro-movement liquid column balance coulometric BOD measuring device

technical field

The invention belongs to the technical field of detection, and relates to a BOD measuring device, in particular to a pressure difference micro-movement liquid column balance type coulometric method BOD measuring device.

Background technique

BOD (short for Biochemical Oxygen Demand): biochemical oxygen demand or biochemical oxygen demand (generally refers to five-day biochemical oxygen demand), a comprehensive index indicating the content of aerobic pollutants such as organic matter in water. Biochemical oxygen demand (BOD) is an environmental monitoring indicator, mainly used to monitor the pollution status of organic matter in water bodies. Generally, organic matter can be decomposed by microorganisms, but when microorganisms decompose organic compounds in water, they need to consume oxygen. If the dissolved oxygen in water is not enough to supply the needs of microorganisms, the water body will be in a polluted state. Therefore, BOD is an index related to environmental protection.

At present, with the expansion of China's chemical products, pesticides and other consumer markets, and the vigorous development of the domestic pesticide industry, pharmaceutical and chemical industries, a large number of new pesticides, medicines and chemical products at home and abroad have been introduced or developed. These include a large number of substances that can cause lasting harm to the environment. According to regulations, before these new substances or potentially dangerous chemicals are put on the market, relevant environmental fate biodegradability evaluations must be done. However, at this stage, the domestic biodegradation test system cannot fully meet the OECD, EPA and domestic registration test standards.

The Chinese invention patent with the application number 201310631376.8 discloses a BOD online measuring instrument, which includes a touch display, a data processing center and a BOD measuring unit. The BOD measuring unit includes a reactor, a temperature control device and a data collector. The temperature control The device is provided with a temperature control chamber, the reactor is located in the temperature control chamber, the reactor is provided with a water inlet pipe and a water outlet pipe, the water inlet pipe is provided with a first flow cell, and the water outlet pipe is provided with a second flow cell. The first flow cell is provided with a first electrode seat, and the first electrode seat is inserted with a first dissolved oxygen electrode; the second flow cell is provided with a first electrode seat, and a second electrode seat is inserted with a second electrode seat. Dissolved oxygen electrode. The technical solution published in this patent mainly uses two dissolved oxygen electrodes to directly measure the dissolved oxygen data of the water quality at two points entering the device. The accuracy of the data depends on the accuracy of the dissolved oxygen electrodes. The test object is mainly water or polluted water. It is mainly used in the field of water quality monitoring, and it is not suitable for evaluating the environmental biodegradability of specific organic chemical substances.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a pressure differential fretting fluid that is easy to operate, stable in performance, easy to disassemble, wash, and replace, and test-related parameters can be automatically monitored, tracked and recorded by a computer Column balance coulometric BOD determination device.

The purpose of the present invention can be achieved through the following technical solutions:

A pressure difference micro-movement liquid column balance type coulometric BOD measuring device, the device includes a constant temperature control unit and a plurality of coulometric BOD measuring units arranged in the constant temperature control unit, the constant temperature control unit includes a constant temperature water bath, set in The temperature probe in the constant temperature water bath, the relay electrically connected to the temperature probe in turn, the data acquisition controller and the cold water heater, the cold water heater is connected with the constant temperature water bath through pipelines, and the multiple coulometric BOD measuring units are all set in the constant temperature water bath. Water bath, and respectively connected with the data acquisition controller through the circuit.

The constant temperature control unit also includes an uninterruptible power supply, which is connected with the hot and cold water heater through a circuit.

There are 6 Coulomb BOD measuring units in total, which are the first Coulomb BOD measuring unit, the second Coulomb BOD measuring unit, the third Coulomb BOD measuring unit, the fourth Coulomb BOD measuring unit, the fifth Coulomb BOD measuring unit and The sixth Coulomb BOD measurement unit is equally spaced in a constant temperature water bath.

Described Coulomb BOD determination unit comprises the magnetic force stirrer that is arranged in constant temperature water bath tank, the sample test bottle that is arranged on the magnetic force stirrer, the copper sulfate electrolyzer that is connected with sample test bottle and the positive pole with copper sulfate electrolyzer, The negative poles are respectively electrically connected to the coulomb counter, and the coulomb counter is also connected to the data acquisition controller through a circuit.

The copper sulfate electrolyzer is an asymmetric U-shaped tube with a positive pole and a negative pole at both ends, and a branch pipe is provided on one side of the asymmetric U-shaped pipe, which is connected with the sample test bottle through the branch pipe.

The anode is a platinum electrode, and the bottom of the platinum electrode is provided with a delay cone for controlling the frequency of electrolyzing copper sulfate, and the anode is a copper electrode.

The delay cone is a delay cone made of hydrophobic PTFE material.

In the working state, the time-delay cone increases the time of the electrolysis process by utilizing the principle of non-wetting and surface tension of the liquid to the hydrophobic material.

The copper sulfate liquid surface in the asymmetric U-shaped tube is provided with liquid paraffin for preventing the liquid surface from evaporating.

The medium to be tested is contained inside the sample test bottle, and a carbon dioxide absorption pool is arranged above the medium.

The carbon dioxide absorption pool is a tray filled with soda lime.

The data acquisition controller is a computer, which is provided with an automatic software control program, which can automatically collect and record the water temperature in the constant temperature water tank and the start and end time of each copper sulfate electrolysis.

According to the requirements of the test standard, the components of the six coulometric BOD determination units are assembled in the same way, the difference is that the substances added to the culture medium in each coulometric BOD determination unit are different, specifically: the first coulometric BOD determination unit and In the second Coulomb BOD determination unit, the culture medium in the sample test bottle contains the microorganisms inoculated and the organic sample to be tested, and in the third Coulomb BOD determination unit, the culture medium in the sample test bottle contains the microorganisms inoculated and the reference For comparison, in the fourth Coulomb BOD determination unit, the culture medium in the sample test bottle contains inoculated microorganisms, reference substances and tested organic matter samples, in the fifth Coulomb BOD determination unit, the sample test bottle The culture medium in contains only inoculated microorganisms, and in the sixth Coulomb BOD determination unit, the culture medium in the sample test bottle only contains tested organic matter samples.

When BOD is measured, a temperature value is first set by the data acquisition controller, and the temperature probe transmits the real-time water temperature information of the constant temperature water bath to the data acquisition controller, and the data acquisition controller passes the received real-time water temperature information through The relay controls the opening and closing of the hot and cold water heater, regulates the water temperature of the constant temperature water bath until the water temperature is stable at the set temperature value, turns on the magnetic stirrer, stirs the culture medium in the sample test bottle, so that the microorganisms can fully contact the culture medium. Organic matter, microorganisms consume oxygen to decompose organic matter, release carbon dioxide, and be absorbed by the carbon dioxide absorption pool, making the pressure in the asymmetric U-shaped tube unbalanced, and the copper sulfate liquid level on the side of the platinum electrode rises and submerges the delay cone. At this time, The coulometer converts the pressure into an electrical signal, turns on the direct current, the data acquisition controller starts to record the electrolysis time, and the platinum electrode starts to electrolyze copper sulfate and release oxygen. When the amount of oxygen increases, the pressure in the asymmetric U-shaped tube gradually tends to balance, and the platinum electrode The copper sulfate liquid level on one side drops, and when the liquid level falls below the connecting surface of the delay cone and the platinum electrode, the electrolysis of copper sulfate stops, and the oxygen generated by electrolysis is added to the sample test bottle, and the copper sulfate electrolysis is calculated according to Faraday's first law Amount, while the consumption of oxygen is proportional to the amount of electrolysis of copper sulfate, and the BOD value can be converted.

The present invention mainly uses the principle of aerobic microorganisms to decompose organic matter to consume oxygen, and utilizes pressure changes to control the opening and closing of the electrolytic copper sulfate device through the time-delay cone, and utilizes Faraday's first law, the consumption of oxygen and the amount of electrolysis of copper sulfate In proportion, by calculating the amount of electrolysis of copper sulfate, the consumption of oxygen is converted and expressed in BOD (Biological Oxygen Demand).

The invention can be used for rapid biodegradation and inherent biodegradation experiments of various organic chemicals, pesticides, and pharmaceutical intermediates, and can be applied to BOD determination of various samples in environmental monitoring and the like. The equipment is simple to operate, has a high degree of automation, and is easy to disassemble, wash, and replace. The relevant parameters of the test can be automatically monitored, tracked and recorded throughout the entire process. Good Laboratory Practice (GLP) test for rapid biodegradation and inherent biodegradation published by the OECD) and the US Environmental Protection Agency (EPA).

Compared with the prior art, the present invention conducts BOD biodegradation tests on various organic substances, and produces carbon dioxide through the decomposition of organic substances by microorganisms, which is absorbed by the carbon dioxide in the top space of the sample bottle, and the pressure difference generated by the "delay cone" Control the electrolytic copper sulfate oxygen supply device to continuously supply oxygen to the microorganisms in the test bottle, and ensure that the test can be carried out for a long time. At the same time, the temperature in the water bath is controlled by the constant temperature water control system to ensure that it is within ±0.5°C of the set temperature; through computer data The monitoring and acquisition recording system can realize automatic monitoring and recording of various test parameters during the operation of the experimental device. At the same time, the test device is equipped with a high-power power supply, which can also run normally for several hours in the case of power failure. The device is aerobic to organic matter. The biodegradation simulation effect is very obvious, and it can meet most of the biodegradation tests of organic matter.

Compared with prior art, the present invention has following characteristics:

1) The BOD biodegradation test is carried out for various organic substances. The organic matter is decomposed by microorganisms to produce carbon dioxide, which is absorbed by the carbon dioxide in the headspace of the sample bottle, and the pressure difference generated is controlled by the "delay cone". The electrolytic copper sulfate oxygen supply device Continuously supply oxygen to the microorganisms in the sample test bottle, and ensure that the test can be carried out for a long time;

2) Due to the use of a constant temperature control unit, it can ensure that the test temperature is stable within the range of ±0.5°C of the set temperature, effectively improving the accuracy of the test;

3) Due to the use of uninterruptible power supply, it can ensure that in the event of a power outage emergency, the entire BOD measuring device can also operate normally for several hours in the event of a power outage, and at the same time ensure that the original test data will not be lost;

4) Due to the use of the data acquisition controller, the automatic monitoring and recording of each test parameter during the operation of the test device can be realized, and the simulation effect on the aerobic biodegradation of organic matter is very obvious, and it can meet most of the biodegradation tests of organic matter;

5) The overall structure is simple and compact, easy to operate, stable in performance, easy to disassemble and wash, and easy to replace. The relevant parameters of the test can be automatically monitored, tracked and recorded by the computer, and can be used for various organic compounds (such as: volatile, photodegradable, Insoluble, etc.) biodegradation test.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2a-2e is the schematic diagram of electrolysis process of delay cone of the present invention;

Instructions for marks in the figure:

1—Constant temperature water bath, 2—Temperature probe, 3—Relay, 4—Data acquisition controller, 5—Cold water heater, 6—Uninterruptible power supply, 7—First Coulomb BOD measurement unit, 71—Magnetic stirrer, 72— Sample test bottle, 721—medium, 722—carbon dioxide absorption pool, 73—copper sulfate electrolyzer, 731—positive electrode, 732—negative electrode, 733—delay cone, 734—branch, 74—coulomb meter, 8—second coulomb BOD measurement unit, 9—third coulomb BOD measurement unit, 10—fourth coulomb BOD measurement unit, 11—fifth coulomb BOD measurement unit, 12—sixth coulomb BOD measurement unit.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example:

As shown in Figure 1, a differential pressure micro-movement liquid column balance type coulometric BOD measuring device, the device includes a constant temperature control unit and a plurality of Coulomb BOD determination units arranged in the constant temperature control unit, the constant temperature control unit includes a constant temperature water bath 1. The temperature probe 2 arranged in the constant temperature water bath 1, the relay 3 electrically connected to the temperature probe 2 in sequence, the data acquisition controller 4 and the cold water heater 5, the cold water heater 5 is connected with the constant temperature water bath 1 through pipelines, and more Each coulometric BOD measuring unit is set in the constant temperature water bath 1, and is respectively connected with the data acquisition controller 4 through the circuit.

Wherein, the constant temperature control unit also includes an uninterruptible power supply 6, which is connected to the cold water heater 5 through a circuit; there are 6 coulometric BOD measuring units, which are respectively the first coulombic BOD measuring unit 7 and the second coulombic BOD measuring unit. The unit 8 , the third coulomb BOD measurement unit 9 , the fourth coulomb BOD measurement unit 10 , the fifth coulomb BOD measurement unit 11 and the sixth coulomb BOD measurement unit 12 are equally spaced in the constant temperature water bath 1 .

Coulomb BOD determination unit comprises the magnetic stirrer 71 that is arranged in constant temperature water bath 1, the sample test bottle 72 that is arranged on the magnetic stirrer 71, the copper sulfate electrolyzer 73 that communicates with sample test bottle 72 and the copper sulfate electrolyzer The positive pole 731 and the negative pole 732 of 73 are respectively electrically connected to the coulomb counter 74, and the coulomb counter 74 is also connected to the data acquisition controller 4 through a circuit.

Copper sulfate electrolyzer 73 is the asymmetric U-shaped tube that is respectively provided with positive pole 731, negative pole 732 at two ends, and this asymmetrical U-shaped tube one side is provided with branch pipe 734, and communicates with sample test bottle 72 by branch pipe 734; Positive pole 731 is Platinum electrode, the bottom of the platinum electrode is also provided with a delay cone 733 for controlling the frequency of electrolytic copper sulfate, and the negative electrode 732 is a copper electrode; the delay cone 733 is a delay cone 733 prepared from hydrophobic PTFE material; Next, the delay cone 733 uses the principle of non-wetting and surface tension of the liquid to the hydrophobic material to increase the time of the electrolysis process; the copper sulfate liquid surface in the asymmetric U-shaped tube is provided with liquid paraffin to prevent the liquid surface from evaporating. .

The medium 721 to be tested is contained inside the sample testing bottle 72, and a carbon dioxide absorption pool 722 is arranged above the medium 721, and the carbon dioxide absorption pool 722 is a tray filled with soda lime.

The data acquisition controller 4 is a computer, which is provided with an automatic software control program, which can automatically collect and record the water temperature in the constant temperature water tank and the time of the beginning and end of each copper sulfate electrolysis.

In this implementation, the constant temperature water bath 1 is a glass water bath or a stainless steel water bath, and the constant temperature water bath 1 is arranged on a main frame, the main frame is made of SUS304 stainless steel with a thickness of 2mm, and the bottom feet of the frame are equipped with movable casters , movable brake fixed.

According to the requirements of the test standard, the components of the 6 coulometric BOD measurement units are assembled in the same way, the difference is that the medium 721 in each coulometric BOD measurement unit has different substances added, specifically: the first coulomb BOD measurement unit 7 and the second coulomb BOD measurement unit In the second Coulomb BOD determination unit 8, the culture medium 721 in the sample test bottle 72 comprises the microorganisms inoculated and the tested organic matter sample, and in the third Coulomb BOD determination unit 9, the culture medium 721 in the sample test bottle 72 comprises the microorganisms inoculated And reference substance, in the 4th Coulomb BOD determination unit 10, the culture medium 721 in the sample test bottle 72 comprises the microorganism of inoculation, reference substance and the organic matter sample that is tested, in the 5th Coulomb BOD determination unit 11, sample test bottle The culture medium 721 in 72 only contains inoculated microorganisms, and in the sixth coulometric BOD measurement unit 12, the culture medium 721 in the sample test bottle 72 only contains the organic matter sample to be tested.

In the actual use process, different software was written to control and record the water bath temperature and electrolysis time, and at the same time, the collected data was directly calculated by the software to calculate the BOD value of the microbially decomposed organic matter sample.

When BOD is measured, a temperature value is first set by the data acquisition controller 4, and the temperature probe 2 transmits the real-time water temperature information of the constant temperature water bath 1 to the data acquisition controller 4, and the data acquisition controller 4 is based on the received real-time water temperature. The information controls the opening and closing of the hot and cold water heater 5 through the relay 3, regulates the water temperature of the constant temperature water bath 1 until the water temperature is stable at the set temperature value, turns on the magnetic stirrer 71, and stirs the culture medium 721 in the sample test bottle 72, The microorganisms are fully exposed to the organic substances in the culture medium 721, and the microorganisms consume oxygen to decompose the organic substances, release carbon dioxide, and be absorbed by the carbon dioxide absorption pool 722, so that the pressure in the asymmetric U-shaped tube is unbalanced, as shown in Figures 2a-2e, platinum The copper sulfate liquid level on the electrode side rises and submerges the delay cone 733. At this time, the coulometer 74 converts the pressure into an electrical signal, turns on the direct current, and the data acquisition controller 4 begins to record the electrolysis time, and the platinum electrode begins to electrolyze the copper sulfate and release Oxygen, when the amount of oxygen increases, the pressure in the asymmetric U-shaped tube gradually tends to balance, and the copper sulfate liquid level on the side of the platinum electrode drops, and when the liquid level drops below the connecting surface of the delay cone 733 and the platinum electrode, the copper sulfate stop, the oxygen produced by electrolysis is added to the sample test bottle 72, and the amount of copper sulfate electrolysis is calculated according to Faraday's first law, and the consumption of oxygen is proportional to the amount of copper sulfate electrolysis, and the BOD value can be converted.

The differential pressure micro-movement liquid column balance coulometric BOD measuring device of this embodiment can be used for rapid biodegradation and inherent biodegradation experiments of various organic chemicals, pesticides, and pharmaceutical intermediates, and can be applied to environmental monitoring of various samples. BOD determination, etc. The device is simple to operate, has a high degree of automation, and is easy to disassemble, wash, and replace. The relevant parameters of the test can be monitored, tracked and recorded automatically throughout the entire process. Good Laboratory Practice (GLP) test for rapid biodegradation and inherent biodegradation published by the OECD) and the US Environmental Protection Agency (EPA).

Claims (10)

1. A pressure difference micro-movement liquid column balance type coulometric method BOD measuring device, the device comprises a constant temperature control unit and a plurality of Coulomb BOD determination units arranged in the constant temperature control unit, it is characterized in that, the described constant temperature control unit comprises A constant temperature water bath (1), a temperature probe (2) arranged in the constant temperature water bath (1), a relay (3) electrically connected to the temperature probe (2) in sequence, a data acquisition controller (4) and a cold water heater (5 ), the cold water heater (5) communicates with the constant temperature water bath (1) through pipelines, and the multiple Coulomb BOD measurement units are all arranged in the constant temperature water bath (1), and are respectively connected with the data acquisition controller ( 4) Connect. 2. A kind of differential pressure fretting liquid column balance type coulometric method BOD measuring device according to claim 1, is characterized in that, described constant temperature control unit also comprises uninterruptible power supply (6), and this uninterruptible power supply (6 ) is connected with the hot and cold water heater (5) through the circuit. 3. A kind of differential pressure fretting liquid column balance type coulometric BOD measuring device according to claim 1, it is characterized in that, described coulombic BOD measuring unit is provided with 6 altogether, and is equally spaced and arranged in constant temperature water bath (1). 4. A kind of differential pressure fretting liquid column balance type coulometric method BOD determination device according to claim 3, is characterized in that, described coulometric BOD determination unit comprises the magnetic stirrer that is arranged in the constant temperature water bath (1) (71), the sample test bottle (72) that is arranged on the magnetic stirrer (71), the copper sulfate electrolyzer (73) that communicates with the sample test bottle (72) and the positive pole (73) with the copper sulfate electrolyzer (73) 731), the negative pole (732) is respectively electrically connected to the coulomb counter (74), and the coulomb counter (74) is also connected to the data acquisition controller (4) through a circuit. 5. a kind of differential pressure fretting liquid column equilibrium type coulometric method BOD measuring device according to claim 4, is characterized in that, described copper sulfate electrolyzer (73) is that two ends are respectively provided with positive pole (731), The asymmetrical U-shaped tube of the negative electrode (732), one side of the asymmetrical U-shaped tube is provided with a branch pipe (734), and communicates with the sample test bottle (72) through the branch pipe (734). 6. A kind of differential pressure fretting liquid column balance type coulometric method BOD measuring device according to claim 5, is characterized in that, described positive pole (731) is platinum electrode, and the bottom of this platinum electrode is also provided with for controlling electrolysis. The time-delay cone (733) of copper sulfate frequency, and the negative electrode (732) is a copper electrode. 7. A kind of differential pressure fretting liquid column balance type coulometric method BOD measuring device according to claim 5, is characterized in that, the copper sulfate liquid surface in the described asymmetrical U-shaped tube is provided with for preventing liquid surface Evaporated liquid paraffin. 8. A kind of differential pressure micro-movement liquid column equilibrium coulometric method BOD measuring device according to claim 4, it is characterized in that, described sample test bottle (72) inside dresses the culture medium (721) to be tested, the A carbon dioxide absorption pool (722) is provided above the culture medium (721). 9 . A differential pressure micro-motion liquid column balance coulometric BOD measuring device according to claim 8 , characterized in that, the carbon dioxide absorption pool ( 722 ) is a tray filled with soda lime. 10. A kind of differential pressure micro-movement liquid column balance type coulometric method BOD measuring device according to any one of claims 1 to 9, characterized in that, when BOD is measured, the data acquisition controller (4) is first set Set a temperature value, the temperature probe (2) transmits the real-time water temperature information of the constant temperature water bath (1) to the data acquisition controller (4), and the data acquisition controller (4) passes through the relay according to the received real-time water temperature information (3) Control the opening and closing of the cold water heater (5), regulate the water temperature of the constant temperature water bath (1), until the water temperature is stable at the set temperature value, open the magnetic stirrer (71), and stir the sample test bottle (72 ) in the culture medium (721), so that the microorganisms fully contact the organic matter in the culture medium (721), the microorganisms consume oxygen to decompose the organic matter, and release carbon dioxide, which is absorbed by the carbon dioxide absorption pool (722), making the asymmetric U-shaped tube pressure imbalance, the copper sulfate liquid level on the platinum electrode side rises and submerges the delay cone (733), at this time, the coulometer (74) converts the pressure into an electrical signal, turns on the direct current, and the data acquisition controller (4) starts recording During the electrolysis time, the platinum electrode begins to electrolyze copper sulfate and release oxygen. When the amount of oxygen increases, the pressure in the asymmetric U-shaped tube gradually tends to balance, and the copper sulfate liquid level on the side of the platinum electrode drops. When the liquid level drops to the delay cone ( When 733) is below the connection surface of the platinum electrode, the electrolysis of copper sulfate stops, and the oxygen produced by electrolysis is added to the sample test bottle (72), and the amount of electrolysis of copper sulfate is calculated according to Faraday's first law, and the consumption of oxygen is related to the amount of electrolysis of copper sulfate. In direct proportion, the BOD value can be converted.